Vacuum arc furnace

ABSTRACT

A furnace for consecutive primary melting and secondary remelting is fitted with a cooler and an ingot withdrawal gear mounted on a supporting swing column and has a changeable mould with a stationary base plate for the secondary remelting of metal; the mould is set up on the said column instead of the cooler and the ingot withdrawal gear.

United States Patent 1 Lugovoi et al.

[ 11 3,732,915 1 May 15, 1973 i541 IVACUUM ARC FURNACE Inventors:Anatoly 1 Ivanovich Lugovoi, 4 Minaevsky proezd, 6, kv. I, Moscow;Grigory Alexandrovich Kharatian, Khotkovo, ulitsa Lenina, 4, kv. l3,Moskovskaya oblast;

' Boris Izidorovich Izraelson, Junykh Lenintsev, 92, kv. 49; VeraNikolaevna Kvashnina, Dmitrovskoe shosse, 7/2, kv. 127, both of Moscow,all of U.S.S.R.

22 Filed: Oct.7, 1971 21 Appl.No.: 187,271

52 U.S.Cl ..164/252 51 lnt.Cl. ..B22d 27/02 Field of Search ..164/50,52, 250, 7 164/252; 13/9 [56] References Cited UNITED STATES PATENTS3,190,949 6/1965 Gruber et al. 1 3/31 3,235,373 2/1966 Poole et al..75/10 3,341,321 9/1967 Morrison et al. ..75/l2 3,523,995 8/1970 Tulinet al. ..l64/252 FOREIGN PATENTS OR APPLICATIONS 1,200,278 7/1970 GreatBritain 1 64/252 Primary ExaminerJ. Spencer Overholser AssistantExaminer-John E. Roethel A ttorney- Holman & Stern 57] ABSTRACT Afurnace for consecutive primary melting and secondary remelting isfitted with a cooler and an ingot withdrawal gear mounted on asupporting swing columnand has a changeable mould with a stationary baseplate for the secondary remelting of metal; the mould is set up on thesaid column instead of the cooler and the ingot withdrawal gear.

1 Claim, 2 Drawing Figures VACUUM ARC FURNACE BACKGROUND OF THEINVENTION 1. Field of the Invention The present invention relates to thefield of metal lurgy, more particularly to electric arc furnaces formelting metals and their alloys.

2. Description of the Prior Art For the production of high-grade metalsandtheir alloys arc melting under vacuum is used.

Widely known is a vacuum arc furnace for melting ingots by smelting aconsumable electrode.

The above said furnace incorporates a melting chamber with an.rod-electrode holder inverted in it, a mould adjacent to the chamber andfitted with a movable base plate under which are located a cooler and aningot withdrawal gear overhung from a supporting column and capable oftravelling vertically, all the aforesaid components disposedin anair-tight furnace shell.

The furnace serves for the primary remelting of the electrode, made frompressed (of the comminuted ore with requisite additions) zirconium, toproduce an ingot for the secondary remelting process.

In order to improve pumping conditions when venting and removing gasescopiously liberated during melting the melting zone of the foregoingfurnace is arranged close to a connecting vacuum system.

As the ingot is built up, the ingot withdrawal gear transfers it intothe cooler.

Secondary remelting of the ingot formed is effected in a separate vacuumarc furnace having a mould with a stationary base plate.

Hence for producing a commercial ingot the shop shall be equipped withtwo furnaces: one for primary and another for secondary remelting.

However, the use of two furnaces is not justified in all cases,especially for the small-lot production of ingots.

In practice there is the need for carrying both the first and the secondremelting operations in a single furnace which would ensure a saving inthe area of the production floor, and ensure more efficient usage ofstandard equipment and a reduction in readiness time in the course ofproduction.

SUMMARY OF THE INVENTION It is an object of the present invention todevelop a construction of an electric furnace which would enable boththe primary and secondary remelting operations to be accomplished in it.

According to the specified and other objects in a vacuum arc furnaceincorporating the invention the following elements are set up in anair-tight furnace shell: a melting chamber with a rod-electrode holderinserted in the chamber, a mould adjacent to said chamber and having amovable base plate under which are mounted a cooler and an ingotwithdrawal gear overhanging from a supporting column and capable ofshifting verti cally; in accordance with this invention, the supportingcolumn is'free to swing about its axis and is suited for the removalofboth the color and the ingot withdrawal gear when they are positionedby the column rotation on .a discharging axis and a changeable mould isprovided fitted with a stationary base plate and intended for the secondremelting of the metal, with the mould overhanging from the said columnto replace the mould equipped with the movable base plate, the coolerand the ingot withdrawal gear.

The changeable units and gears as well as the use of a column for ingotdischarging will'permit both the first and the-second remeltingoperations to be carried out in one and the same furnace.

BRIEF DESCRIPTION 01% THE DRAWING Described below is an exemplaryembodiment of the invention to be considered with reference to theaccompanying drawings, in which:

FIG. 1 depicts a side view of a vacuum arc furnace, conforming to theinvention, with a mould and a movable base plate; I

FIG. 2 is a vertical section through the axis of a furnace fitted withamould and a stationary base plate.

A furnace incorporates protective shell 1 (FIG. 1) of a weldedconstruction made from rolled section and sheet steel and fitted withenclosed platforms (not shown in the drawing) for furnace attendance.

Located within the shell is melting chamber 2 which is a weldedwater-cooled cylindrical casing with an interior made of two-layersteel.

Melting'chamber 2 communicates with a vacuum system 3 (FIG. 2).

Through the upper portion of melting chamber 2 is passed a holder 4 to arod-electrode linked with rod travelling gear 5.

Travelling gear 5 of rod-electric holder 4 is made as a single screwenclosed in the rod and operated by drive 6 with a differential reducinggear.

Travelling gear 5 of rod-electrode holder 4 ensures positive forcedtravel of the electrode.

Butting against the lower part of melting chamber 2 is mould 7 fittedwith a movable base plate and made up of a copper flanged mould mountedin a steel case with a solenoid. For adjusting the level of liquid metalaround mould 7 are positioned level gages (not shown in the drawing).

As the ingot is progressively built-up the movable base plate of mould 7is shifted by ingot withdrawal gear 8 into cooler 9; v

The latter consists of two cylindrical shells with a cavity between themdesigned for cooling water circulation.

Mould 7 and cooler 9 overhung from carriage 10 are 1 free to movevertically along supporting column 11 made from a steel tube. v

For carrying out the second remelting, cooler 9 and ingot withdrawalgear 8 are stripped and replaced by changeable mould l3 equipped with .astationary base plate and a bracket 12 fixed on supporting column 11.

Mould 13 withthe stationary base plate comprises a copper flanged mouldinstalled in a non-magnetic steel case and fitted with a solenoid woundaround its exterior and intended for stabilizing arcing.

The base plate of mould 13 is produced in the form of a stampedcoppersleeve anda steel bottom forming a cavity for cooling purposes.

In the lower part of column 111 is located swinging gear 14 of column11' which serves for rotating said column about its axis and assures thedischarge of the ingot produced.

Swinging gear 14 ismade up ofa hydraulic cylinder mounted at thebase ofcolumn 11 with a rod mechanically linkedwith a shackle (not shown in thedrawing) provided at the base of column 11.

The furnacemay be provided with a mould cleaning device constituted 'bya steel pillar with arranged thereon brushes and operated by a hydrauliccylinder and a drive.

An electric circuit of the furnace provides for remote control of thefurnace gears, for automatic or manual control of the melting process,there is also an alarm and interlocking system.

The setup functions as follows.

For producing an ingot by primary remelting vacuum melting chamber 2 isconnected to mould 7 with a movable base plate.

By swinging'column 11 about its axis, the cooler 9 with ingot withdrawalgear 8 is moved outside protective shell 1. Then an electrode is loweredin cooler 9 with the aid of a shop crane and by rotating column 11 inthe opposite direction both the cooler 9 together with the electrode andingot withdrawal gear 8 are returned to their initial position in shell1 and set up under mould 7, fitted with the movable base plate,coaxially with the mould.

Next, by shifting carriage 10, the cooler 9 is raised until it buttsagainst mould 7.

The electrode is connected to the rod-electrode holder 4, whereupon therod travelling gear 5 of rodelectrode holder 4 suspends the electrode inmelting chamber 2. Now a door of the protective shell 1 is closed.

On forcing cooler 9 tightly against mould 7 the furnace is evacuatedafter which power is fed to strike an arc.

As the ingot is built-up, ingot withdrawal gear 8 transfers it intocooler 9. When the melting process is completed, the ingot which ischilled in cooler 9, is moved to the discharging axis where thehydraulic cylinder of ingot withdrawal gear 8 pulls it from cooler 9,whereupon it is handled by a shop crane to a point where furtherprocessing will occur.

When using the furnace for the secondary remelting operation, the ingotproduced is not discharged but connected instead to rod-electrode holder4 (FIG. 2) to be suspended in melting chamber 2. Next, the mould 7 withthe movable base plate is detached from the melting chamber, cooler 9and ingot withdrawal gear 8 arestripped from carriage 10 and replaced bymould 13 with the stationary base plate which is overhung from thecarriage.

By swinging column 11, the mould 13 is positioned coaxially with meltingchamber 2, after which carriage 10 raises it to butt against thechamber. A tightening gear (not shown in the drawing) of mould 13 iscoupled to melting chamber 2.

Then the door of protective shell 1 is closed and the furnace evacuated.

Following this step, power is supplied to strike an arc. Flashing off inthe arc the electrode (the ingot produced after first remelting) buildsup a second remelting ingot into mould 13.

The melting process completed, power is switched off to extinguish thearc.

When the ingot which is produced in mould 13 with the stationary baseplate, is cooled in vacuum (or in an inert atmosphere), air is admittedinto the furnace. Mould 13 with the ingot contained therein is carriedoff melting chamber 2 with the aid of carriage 10 (after disconnectingthe tightening gear). The door (not shown in the drawing) if theprotective shell 1 is then opened. By swinging column 11 the mould 13 ispositioned on the discharging axis where the base plate is detached frommould 13, the cylindrical portion of the mould is taken off and theingot built-up which is supported on the base plate is handled by theshop crane for further processing.

The herein proposed construction of a vacuum arc furnace enables boththe first and the second melting operations to be carried out in one andthe same furnace, and ensures a saving in production area, effectiveusage of standard equipment and an increase in yield of the operatingfurnaces.

What is claimed is:

l. A vacuum arc furnace for consecutive primary melting and secondaryremelting, comprising the following elements located in an air-tightshell: a melting chamber; a rod-electrode holder lowered from above intothe said melting chamber; a first mould with a movable base platebutting against said melting chamber and used for primary melting forforming an ingot from molten metal; a cooler disposed under said firstmould and disposed overhangingly to move vertically along a supportingcolumn having means to cause axial rotation thereof and to strip anddisengage said cooler from said column; a replaceable ingot withdrawalgear, disposed overhangingly of said column and capable of travellingvertically along the said column; a replaceable second mould having astationary base plate overhanging to be free to move in a verticaldirection along said column under the said melting chamber, saidreplaceable second mould being used in place of said first mould and forsecondary melting.

1. A vacuum arc furnace for consecutive primary melting and secondaryremelting, comprising the following elements located in an air-tightshell: a melting chamber; a rod-electrode holder lowered from above intothe said melting chamber; a first mould with a movable base platebutting against said melting chamber and used for primary melting forforming an ingot from molten metal; a cooler disposed under said firstmould and disposed overhangingly to move vertically along a supportingcolumn having means to cause axial rotation thereof and to strip anddisengage said cooler from said column; a replaceable ingot withdrawalgear, disposed overhangingly of said column and capable of travellingvertically along the said column; a replaceable second mould having astationary base plate overhanging to be free to move in a verticaldirection along said column under the said melting chamber, saidreplaceable second mould being used in place of said first mould and forsecondary melting.